1. Filed of the Invention
The present invention relates to a tailgate for a vehicle. More particularly, the present invention relates to a dual-mode tailgate having an improved frame structure. The present invention finds particular application as a tailgate for a pick-up truck and will be described with particular reference thereto. However, it is to be appreciated that the invention may relate to other similar environments and applications.
2. Description of the Prior Art
Dual-mode tailgates are generally known. For example, U.S. Pat. No. 3,387,406 issued to Coker discloses a dual-mode tailgate for use on a station wagon. “Dual-mode” refers to the two directions or pivot axes along which a dual-mode tailgate is openable. More particularly, a dual-mode tailgate is selectively openable in a first, fold-down direction about an axis generally parallel with a bottom edge of the tailgate similar to a conventional pick-up truck tailgate. The dual-mode tailgate is also selectively openable in a second, side-to-side direction about an axis generally parallel with a lateral edge of the tailgate.
It has been proposed to include a dual-mode tailgate in a heavy duty vehicle designed to carry large loads and/or heavy load-bearing cargo. For example, a dual-mode tailgate could be employed in a pick-up truck, a hybrid vehicle that includes a pick-up style bed or other similar vehicle. However, heretofore, most dual-mode tailgates were only employed in light duty vehicles such as station wagons, traditional sport utility vehicles (SUVs) and the like. Thus, the prior art dual-mode tailgates are generally not designed to accommodate large loads or load-bearing cargo and are unsuitable for use on vehicles intended to carry heavy loads.
More particularly, the prior art dual-mode tailgates generally do not have a structural strength sufficient for supporting a relatively heavy load without increasing the likelihood of damage to the tailgate or the vehicle carrying the tailgate, particularly when the tailgate is in its fold-down position. Accordingly, there is a need for a dual-mode tailgate having a relatively high structural strength compared to prior art dual-mode tailgates, particularly when the tailgate is used in its fold-down position.
Additionally, prior art dual-mode tailgates generally have a torsional stiffness and strength that is insufficient to meet the demands required of a tailgate employed in a heavy duty application. Likewise, conventional single-mode tailgates generally do not have sufficient torsional stiffness and strength due, at least in part, to their reliance on a pair of full-time support cables extending from the lateral ends of the tailgate. Thus, there is a further need for a dual mode tailgate that has an increased torsional stiffness and strength.
More particularly, dual-mode tailgates generally cannot have a pair of full-time support cables extending from the lateral sides of the tailgate because the dual-mode tailgate needs to be able to swing open. Thus, it is desirable for the dual-mode tailgate employed in a heavy duty vehicle to be sufficiently torsionally stiff and strong such that it could be optionally supported with only a single support cable when in the fold-down position.
The need for increased torsional stiffness and strength are necessitated by the possibility of one lateral edge of the dual-mode tailgate being unsupported away from a fold-down axis when the tailgate is in the fold-down position. For example, if any downward loading is applied near the distal end of the unsupported lateral edge, i.e., the outer corner of the tailgate adjacent the unsupported lateral edge, a relatively large torsional force or load will act across the tailgate. To absorb any such large torsional loads, the tailgate structure is desirably torsionally stiff and strong for purposes of preventing damage to the tailgate and/or the vehicle carrying the tailgate. It is further desirable, due to preferred design parameters, to provide a dual-mode tailgate with increased torsional stiffness and strength without unduly increasing the thickness of the tailgate. Additionally, any improvements that reduce manufacturing costs, increase manufacturing efficiency, decrease the overall weight of the tailgate while maintaining or improving the hem quality of the tailgate and the fit and finish of the overall vehicle and/or improve the reliability of the tailgate are also deemed desirable.